Yet Another Early Master Cylinder Thread

Dane, I don't have any floor pedals around here anymore..........if you give me the measurements I'll run them through my program here that will tell you what the correct size bore the master should be along with the correct height and ratio of the pedal set.

 

The brake arm from the pedal rod to the pivot for the mc rod is 12".
At the mc pivot, it is 3" on-center to the support / pivot at about a 30 degree offset (didn't use my protractor, close guess).
the brake pedal rod is about 6" from the brake arm.

Ill snap a pict in a bit

 

X / Y would be much easier for me.

 

Do didn't think of that, good idea. I'll do that after munchkin falls asleep.

 

X-Y quickie. 0,0 bottom left.

 

Dane,...........First off the drawings I provided above more closely resembles the drawing on the left but inverted for floor pedals............so the "X" dimension should be the length from the center of the fulcrum / pivot point to where the Pedal push plate will attache..........If I'm looking at your drawing on the lower scale that seems to be about 13.750" is that correct? And on the same scale the distance between the fulcrum and the push rod point to the master cylinder would be the "Y" dimension or 2" is that correct? Take the two dimension's and divide them into each other and the ratio is 6.87:1 which is right in the ball park for a manual brake system needs for mechanical advantage. Did you post the Master Cylinder bore size?...........If not I need that also.

 

Terry,

Many thanks! Yes, that's what I'm seeing too. My CAD and perspective drawing skills are way out of date (not had a use / formal CAD drawing anything since mid-90's). I 'traced' the lever in my best known fashion, and then applied a square to the drawing and put some dimensions on there... it's as close to 'scale' as it gets if I kept my pencil in the same vertical perspective on the casting as I followed it around.

I've seen two different 'stock' MC cylinder sizes: 7/8" and 1" for this application. I've not seen the larger bore sizes (not sure more volume is needed). I'm slowly figuring this out - from what I'm seeing (inference here) the smaller brakes (9" and 10") are using the 7/8" application, and the 11" drums are using the 1" MC bore - this is a 'feeling' from what I've read, looked at online, parts number conversion for the later models and so on, but I've not been keeping a list).



On other fronts:
re: from Raybestos:
My Question: looking for MC36365. Is it still in production? Where can I find it? Thanks

their answer: It is obsolete and has not been superseded.

(info on the MC is here: http://www.raybestosbrakes.com/magnoliaPublic/home/catalog/product.html?partNumber=MC36365)
and shows:
[TABLE]
[TR]
[TH]Part Number:[/TH]
[TD]MC36365[/TD]
[/TR]
[TR]
[TH]Brand Name:[/TH]
[TD]Raybestos[/TD]
[/TR]
[TR]
[TH]Part Description:[/TH]
[TD]Brake Master Cylinder[/TD]
[/TR]
[TR]
[TH]Bore Diameter:[/TH]
[TD]7/8" & 1"[/TD]
[/TR]
[TR]
[TH]Number of Outlets:[/TH]
[TD]2[/TD]
[/TR]
[TR]
[TH]Primary Outlet Thread:[/TH]
[TD](1) 3/8-24[/TD]
[/TR]
[TR]
[TH]Secondary Outlet Thread:[/TH]
[TD](1) 3/8-24[/TD]
[/TR]
[TR]
[TH]Packaged Weight:[/TH]
[TD]7.57"[/TD]
[/TR]
[TR]
[TH]Packaged Length:[/TH]
[TD]11.00"[/TD]
[/TR]
[TR]
[TH]Packaged Height:[/TH]
[TD]5.25"[/TD]
[/TR]
[TR]
[TH]Packaged Width:[/TH]
[TD]7.37"[/TD]
[/TR]
[TR]
[TH]Grade Description:[/TH]
[TD]Premium[/TD]
[/TR]
[/TABLE]

 

No Problem, just wanted to see if you had purchased a MC yet.............so don't until I run this info.

 

Dane,

On your brake system: 11"x2" inch drum brakes F/R........ front using the 1.125" bore & rear using the 15/16" bore wheel cylinders is fine......Your Pedal ratio is about 6.87:1. The CJ of that era was about 6.6:1. As far as your floor mounted Master Cylinder a later dual Reservoir style should be used and as we have communicated via PM's it seems you already have one in mind.

Bore size in the Master could either be 7/8" or 1". The system you have now using the 11" drums , mirrors the mid seventies CJ package and for the most part they used a 1" bore Master and after running the pressure calculations again either would be OK...............

But, If you were thinking of ever going to a larger sized & heavier wheel and tire combination other than a near stock OEM size as you now have , the 7/8" bore may be a better choice simply from the standpoint of a little increase in brake pressure as a result of the smaller bore would be welcomed to help control the larger tires during a stop.

 

Terry,

Many thanks for your help and insight.

Having assistance from our membership here makes this site so invaluable, especially for those of us 'dabbling' or 'meddling' well outside our own wheelhouses or fenderwells per se.

Cheers.

Dane

 

Dane,
What master cylinder did you decide to go with?

 

Leaning to wilwood dual with remote reservoirs so I don't have to monkey around with the port hole on the floor by the pedals for filling, checking, etc.

i see it in 1" on wilwood so that's likely my choice.

http://www.summitracing.com/parts/wil-260-7563

 

Did you complete the install of the Summit MC?

I have a 69 and am thinking about going with the mc59802, IF I can locate it...

 

Will be using the wilwood 1" with remote cylinders. Left a good job for a great opportunity, not just a new job recently and no time to tinker.

Tarry99 helped me confirm with my choice for wheel cylinders that it'll work.

Dane

 

I am adding this post for reference only... For those that may be searching for a replacement. Thanks Danefraz for the info, with it I found what I needed.

My '69 had a Wagner FF-50314 and I replaced it with a Crown J0945556 on got on eBay from "eastcoastjeepsstore".

 

I also have a 71, stock 225 etc. the brakes are set up just as focker described his. Does anyone now what that copper splitter, thats not a splitter, (two lines in two out), not like any reducer I've ever seen, what it is and what its for? Im about to replace the MC in mine. Going down list of old parts, trying to fix brake lights that stick on after driving shortly, but go off and work as should after sitting for short while. Any ideas welcome, Thank's